Three suicide bombers in Pakistan hit a government site in Peshawar Friday, in what is believed to be part of a Taliban campaign against an expected army offensive.

The attackers carried out two separate bombings outside a police compound Friday, killing at least 13 people, including at least three police officers, two women and one child. No one has claimed responsibility.

Taliban militants are blamed for a string of attacks that have killed more than 150 people in the last two weeks.

Taliban leaders say the campaign is in retaliation for an army offensive that is expected to begin soon against insurgent strongholds in South Waziristan, near the Afghan border.

Top military and political leaders met in Islamabad Friday to discuss the wave of violence, the possible operation in South Waziristan, and the displacement of people in the region. Officials did not give a date for the anticipated offensive.

The United Nations refugee agency reports thousands of people are fleeing South Waziristan to escape anticipated violence. U.N. agencies estimate more than 100,000 people in the region have been displaced since May.

A spokesman for the U.N. refugee agency, Andrej Mahecic, says officials do not expect the outflow from South Waziristan to reach the scale in Swat Valley. More than two million people fled Swat earlier this year when the government began an offensive against militants in the region.

The spokesman said the refugee agency is working with local partners to distribute relief supplies, including sheets, sleeping mats and kitchen sets to those now fleeing South Waziristan.

But U.N. agencies say the deteriorating situation in Pakistan is hindering their humanitarian operations. A spokesman for the World Health Organization, Paul Garwood, says there is currently a lack of water in health facilities and a shortage of medical funding.